1. Technical Field
The present invention relates to an analysis device, an analysis method, an optical element and an electronic apparatus for an analysis device and an analysis method, and a method of designing an optical element.
2. Related Art
In the fields of environment, food, public safety, and the like including the medical and health field, there is a demand for a sensing technique which detects trace substances quickly and simply with high sensitivity and high precision. There are a wide variety of trace substances to be detected, and include, for example, bio-related materials, such as bacteria, viruses, protein, nucleic acids, and various antigens/antibodies, and various compounds including inorganic molecules, organic molecules, and polymers. In the related art, while trace substances are detected by sampling, analysis, and parsing, since a dedicated device is required and an inspection worker needs to be skilled, the analysis in this situation is difficult. For this reason, it takes a lot of time (several days or more) for an inspection result to be obtained. Thus, there is a great need for quick and simple detection, and therefore, it is desirable to develop a sensor which can meet this need.
For example, from expectations of comparative ease of integration and less influence by an inspection and measurement environment, there is a growing interest in a sensor which uses surface plasmon resonance (SPR), or a sensor which uses surface-enhanced Raman scattering (SERS).
For the purpose of sensing with higher sensitivity, as an example of a sensor element having a structure which realizes a hybrid mode, in which both modes of a localized surface plasmon (LSP) and a propagated surface plasmon (PSP) are resonated simultaneously, OPTICS LETTERS, Vol. 34, No. 3, 2009, 244-246 suggests a sensor element, called GSPP (Gap type Surface Plasmon Polariton). OPTICS LETTERS, Vol. 30, No. 24, 2005, 3404-3406 describes the fundamental matters of electromagnetic coupling of LSP and PSP, and discloses an element having a configuration in which LSP and PSP interfere with each other constructively (International Publication No. 2009/002524 and International Publication No. 2005/114298).
The sensor disclosed in International Publication No. 2009/002524 has a layer in which nanoparticles formed on a substrate made of a dielectric are arranged regularly in a lattice shape. The particle layer is an array in which a particle size is 2 nm to 200 nm, if the particles are arranged in a square lattice shape, the particles are arranged at an interval between particles of 50 nm to several μm, and if the particles are arranged so as to form a diffraction grating, the particles are arranged in a row at an interval of 1 nm to 10 nm and at an interval between rows of equal to or greater than 0.1 μm.
The sensor disclosed in International Publication No. 2005/114298 has a vapor deposition layer which is called a resonance mirror on a substrate and is made of silver, gold, or aluminum to have a thickness of 200 nm to 500 nm. Then, the sensor has a dielectric layer which is called a light transmitting layer formed on the vapor deposition layer to have a thickness of smaller than 50 nm, and a particle layer which is called a nanoparticle layer formed on the dielectric layer and has particles of gold, silver, or the like arranged therein. The particle layer is an array in which the particle size is 50 nm to 200 nm, and the particles are arranged regularly at even intervals between particles from an interval smaller than the wavelength of incident light to an interval obtained by adding 0 nm to 20 nm to the particle size.
However, in the sensors disclosed in International Publication No. 2009/002524 and International Publication No. 2005/114298, the relationship between the wavelength or polarization sate of incident light and the arrangement of the array is not taken into consideration, and for this reason, a sufficient signal amplification degree is not necessarily obtained.
Although OPTICS LETTERS, Vol. 34, No. 3, 2009, 244-246 and OPTICS LETTERS, Vol. 30, No. 24, 2005, 3404-3406 suggest a system which uses the interaction between the localized surface plasmon and the propagated surface plasmon, there is a problem in that Hot Spot Density (HSD) is low.